• Korean Journal of Food Science and Technology
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• v.18 no.4
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• pp.288-293
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• 1986

A raw starch-digesting enzyme from Rhizopus oryzae was purified by ammonium sulfate fractionation, DEAE-sephacel column chromatography and Sephadex G-150 gel filtration. The specific activity of purified enzyme was 45.2 Ulmg protein and the yield was 16.2%. The purified enzyme was found to be homogeneous bypolyacrylamide gel electrophoresis and its molecular weight was estimated to be 67,000 by SDS-polyacrylamide gel electrophoresis, and also the enzyme had Km value of 4.082 mg/ml for raw corn starch. The optimal temperature and pH for the enzyme activity were $50^{\circ}C$ and 4.0-5.0, respectively. Reaction product of raw corn starch by purified enzyme was glucose mainly.

• The Korean Journal of Food And Nutrition
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• v.28 no.4
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• pp.586-593
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• 2015

The baking properties of gluten-free rice bread with different percentages of corn starch and waxy corn starch were investigated. The specific gravity and color (L, a, b) of the dough as well as the appearance, color (L, a, b) and texture of the rice bread were analyzed. Replacement of rice flour with 1, 2.5, 5, 7.5 and 10% corn starch did not have a significant effect on the specific gravity and color of the dough. The volume and specific volume of the rice bread showed an increasing trend as the amount of added corn starch increased. The chewiness, gumminess and hardness of the rice bread showed a decreasing trend as the amount of added corn starch increased. Replacement of rice flour with 1, 5 and 10% waxy corn starch did not have a significant effect on the specific gravity and color of the dough. The color of the rice bread showed an increasing trend as the amount of added waxy corn starch increased. These results suggest that replacement of rice flour with 7.5% corn starch or 1% waxy corn starch is effective for gluten-free rice bread.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.1
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• pp.86-91
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• 1987

Changes in the contents of sugars and soluble solids and flavor rate of cooked kernels of three sweet com hybrids (Great Bell, Danok 1, and Golden Cross Bantam) and a super sweet corn hybrid (Crisp Super Sweet 720) were observed from 15 days after silking (DAS) to 27 or 33 DAS in 1985 and 1986 to determine the optimum harvest time. Sucrose content in all hybrids and fructose and glucose contents of Crisp Super Sweet 720 increased from 15 DAS to 21 or 24 DAS and then decreased. However, in the three sweet corn hybrids both fructose and glucose contents were highest at 15 DAS and then continuously decreased with maturity. At harvest time the major sugar component was sucrose and the highest total sugar content of Crisp Super Sweet 720 was 2-3 times higher than that of three sweet corn hybrids. Soluble solids were continuously increased with maturity in three sweet com varieties, but that of Crisp Super Sweet 720 increased up to 24 DAS, maintained the level through 30 DAS and then decreased. At harvest time soluble solids of three sweet com varieties were much higher than that of Crisp Super Sweet 720. The optimum harvest time seems to be about 27 DAS considering flavor rate and marketing conditions although the total sugar content was lower than those of earlier harvests. Soluble solids but not total sugars were positively correlated with the flavor of cooke6 com harvested at different growth stages in the same variety. Total sugars were not correlated with soluble solids or negatively correlated depending on hybrids.

• Journal of Life Science
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• v.28 no.8
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• pp.969-976
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• 2018

In this study, transglucosidase (TG), an enzyme produced by Aspergillus niger, synthesized isomaltooligosaccharide from ${\alpha}-(1{\rightarrow}4)$ linked substrates. The highest TG-producing A. niger KCTC6913 was selected from six kinds of species, and optimized TG producing conditions were established. Five different carbon sources (potato starch, sweet potato starch, corn starch, wheat starch, and dextrin) and three different nitrogen sources (yeast extract, malt extract, and beef extract) were tested to establish the carbon and nitrogen sources favorable for TG production. Measurements of TG activity after an initial culture at pH 5.0 for 15 days revealed that potato starch and yeast extract, which are basic culture media, resulted in the highest TG activity. In addition, A. niger KCTC6913 increased TG production under aerobic conditions and a controlled carbon/nitrogen ratio. In conclusion, to evaluate TG activity in the established optimal medium, it is confirmed that the basal and potato dextrose broth medium were used as a control, and the highest TG production was measured, which was highlighted in the established optimal medium.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.3
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• pp.176-180
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• 2000

The higher sugar and lower starch in super sweet corn may be due to modified endosperm genes sh, bt series, but its seeds have major limiting factors causing low germination and low seedling vigor, This study was conducted to determine what measurable kernel characteristics during the grain tiling period might be more useful as a guide to optimize harvest date for good seed quality in hybrid super sweet corn production. Artificial crossing in super sweet corn hybrid (Chodangok 1) was made on the same day, and ears were harvested from 18 days to 53 days after pollination at weekly intervals. Kernel weight, moisture content, hardness, endosperm rate, seedling height and storage nutrients such as sugars, protein, starch, and germination rate were measured for the kernels at each harvest. Super sweet corn hybrid, Chodangok 1 presented satisfactory germination rate above 70% when harvested on 39 to 46 days after pollination. Its storage nutrients at that time were 23.7-24.2% in starch content 5.5-5.9% in total sugars, 38.9-46.6% in kernel moisture, and 62.7-64.2% in endosperm rate. Germination rate was extremely high when harvested on 39 days after pollination. The black layer of Chodangok 1 could not be used as an indicator for seed harvest. These results suggested that optimum harvest date seems to be 39 days, and kernel moisture and starch content could be used as indications of kernel maturity in deciding when to harvest fer good seed quality in super sweet corn.

• Korean Journal of Food Science and Technology
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• v.23 no.2
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• pp.235-240
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• 1991

Starch phosphates were prepared from the corn starch mixed with 2% sodium tripolyphosphate by twin-screw extruder with a feed rate of 20 kg/hr and an extrusion temperature of $130^{\circ}C$, and the effects of extrusion variables on the physicochemical properties (target parameters) of starch phosphates were investigated. Interrelations of system parameters (specific mechanical energy and extrudate moisture) and rheological properities of starch was analyzed by using the response surface analysis. Degree of substitution (DS) was increased with increasing the feed moisture, and showed the maximum value at the screw of near 250 rpm, Degree of gelatinization was proportionally increased with increasing the screw speed and decreasing the feed moisture. Apparent viscosity of the paste was increased with increasing the feed moisture, but it was not significantly affected by the screw speed. It was found by scanning electron microscopy that the starch microgranules were much more degradaded, and as consequent result, the intrinsic viscosity was decreased, whereas, water solubility index was increased. The rate of retrogradation of the gels was retarded with increasing DS and decreasing viscosity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.556-562
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• 1999

The increasing price of surimi has affected the economical benefits of surimi based food industry, To maintain gel strength in low grade surimi, the optimum formulation adding functional proteins to low grade surimi is required. The objective of this study was to develop the optimum formulation of ingredients in making gels in low grade surimi on the addition of functional non-muscle proteins to low grade surmi by measuring rheological properties of the gels. The rheological qualities of the cooked gels made with A and RA grade surimi on the effects of adding five kinds of starches (potato, wheat, waxy maize, corn and modified corn) and four kinds of functional proteins (bovine plasma protein, dehydrated egg white, soy protein isolate and whey protein concentrate) to the gels were evaluated, The gel styengths at cooking with A and RA grade surimi were decreased with increasing the added starches. The kind of starches added affected little the gel strengths in Rh grade surimi, while potato and corn starches decreased at the least in gel strengths of the gel made with A grade surimi with increasing the concentration of starches. The bovine plasma protein (BPP) significantly increased the gel strength, especially in RA grade surimi, but BPP decreased the whiteness of the gel. Therefore, the optimum content of BPP was up to $2\%$ because of the whiteness of the gels in RA grade surimi, The optimum formulation for the gel with RA grade surimi to satisfy the gel strength of 1000$\times$g and $78\%$ moisture was $40.9\%$ surimi, $9.1\%$ dehydrated egg white (DEW) and $0.9\%$ starch, while that with A grade surimi under the same condition was $37.9\%$ surimi, $6.6\%$ DEW and $3,4\%$ starch.

• Food Engineering Progress
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• v.15 no.2
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• pp.155-161
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• 2011

The aim of this study was to determine the effects of different extrusion conditions on the saccharification characteristics( initial reaction velocity, reaction rate constant, yield) of extruded corn starch. Extruded corn starch-water slurries were mixed with alpha-amylase for the enzymatic saccharification. The saccharification yield of extruded corn starch was high at lower feed moisture content and higher barrel temperature. The solubility of extrudates increased with increase in the SME input which increased with increase in the feed moisture content. Starch hydrolysates having DE 63.8 was obtained after 2 hr reaction. The initial reaction velocity of the extrudate slurry with alpha-amylase was higher with decrease in the feed moisture content. The initial reaction velocity of extruded corn starch was the highest ($2.26{\times}10^{-3}mmol/mL{\cdot}min$) at 25% feed moisture content and $120^{\circ}C$ barrel temperature, 250 rpm screw speed. The pregelatinized starch was $1.83{\times}10^{-3}mmol/mL{\cdot}min$ as a control. Reaction rate constant was a similar trend to initial reaction velocity.

• Korean journal of food and cookery science
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• v.16 no.2
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• pp.188-194
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• 2000

Effects of native and RS-3 type resistant starches prepared from autoclaved-cooled amylomaize VII(AVII) and normal maize starches(NMS) on the rheological and baking properties of wheat flour dough and quality of breads were investigated. In farinogram, water absorption and dough development time were increased, but stability was reduced by the addition of RS. The addition of native starches or resistant starch made from AVII to wheat flour improved the total volume and specific loaf volume of bread compared with the control(no addition), but the addition of NMS-RS reduced those. During the storage of bread at room temperature, the moisture content of control was decreased but those of native starch- or RS-added breads remained constantly. AVII-RS- or NMS-RS-added bread was evaluated to have good overall acceptability compared with control by elementary school students. The addition of enzyme-resistant starch to bread regardless of botanical sources of starch not only improved the overall acceptability and nutritional benefits but also improved the sensory acceptability.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.2
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• pp.93-103
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• 2020

The average growth day of 11 maize varieties from planting to silking in the first cropping (FC) was 89.5 days and in the second cropping (SC) was 46.7 days, which was 43 days faster than in the FC. The average 100-kernel weight (100 KW) in the FC was 28.4 g and 18.3 g in the SC, which was approximately 36.4% lower than that in the FC. The average crude oil content of FC was 3.97% and SC was 3.08%, which was about 0.89% lower than that of FC. The composition of stearic and oleic acid was significantly higher in FC, whereas palmitic and linoleic acid were higher in SC; however, linolenic acid was not statistically different between the two crops. The crude oil content was negatively correlated with linoleic acid (FC -0.264^ns, SC -0.504**) and positively correlated with linolenic acid (0.526**). Unsaturated fatty acid (USFA) composition showed a significant difference between FC (83.48%) and SC (82.96%). Total phytosterol content was 598.3 mg/100 g and 701.9 mg/100 g in FC and SC, respectively, and showed significant difference by planting dates. The β-sitosterol content showed no statistical difference between the planting dates, but campesterol and stigmasterol were significantly higher in SC than in FC. Therefore, it was considered that the temperature condition during the ripening period affects the 100 KW of maize, and this leads to the variation in phytosterol content. However, among phytosterols, β-sitosterol was relatively little affected by the planting dates. USFA composition showed a significantly negative correlation with phytosterol content. Considering the results, the relatively high phytosterol content in SC was mainly because of the delay in progress of starch accumulation as daily air temperature decreased from the middle of the ripening period, whereas progress of phytosterol accumulation in the maize kernel was considered relatively faster than that of starch accumulation.